The invention relates generally to disc drives and more specifically to a disc drive having a movable load ramp operable to raise read/write transducers off of the disc surface when the drive is not in use to maximize disc real estate available for data.
Disc drives are data storage devices that store digital data in magnetic form on a rotating storage medium on a disc. Modern disc drives comprise one or more rigid discs that are coated with a magnetizable medium and mounted on the hub of a spindle motor for rotation at a constant high speed. Information is stored on the discs in a plurality of concentric circular tracks typically by an array of transducers (xe2x80x9ctransducersxe2x80x9d) mounted to a rotary actuator for movement of the transducers relative to the discs. Each of the concentric tracks is generally divided into a plurality of separately addressable data sectors. The read/write transducer, e.g. a magnetoresistive read/write transducer, is used to transfer data between a desired track and an external environment. During a write operation, data is written onto the disc track and during a read operation the transducer senses, i.e., xe2x80x9creadsxe2x80x9d the data previously written on the disc track and transfers the information to the environment external to the head disc assembly. Critical to both of these operations is the accurate locating of the transducer over the center of the desired track.
The transducers are mounted on sliders or heads via flexures at the ends of a plurality of actuator arms that project radially outward from the actuator body. The actuator body pivots about a shaft mounted to the disc drive housing at a position closely adjacent the outer extreme of the discs. The pivot shaft is parallel with the axis of rotation of the spindle motor and the discs, so that the transducers move in a plane parallel with the surfaces of the discs.
Typically, such rotary actuators employ a voice coil motor to position the transducers with respect to the disc surfaces. The actuator voice coil motor includes a coil mounted on the side of the actuator body opposite the transducer arms so as to be immersed in the magnetic field of a magnetic circuit comprising one or more permanent magnets and magnetically permeable pole pieces. When controlled direct current (DC) is passed through the coil, an electromagnetic field is set up which interacts with the magnetic field of the magnetic circuit to cause the coil to move in accordance with the well-known Lorentz relationship. As the coil moves, the actuator body pivots about the pivot shaft and the transducers move across the disc surfaces. The actuator thus allows the transducer to move back and forth in an arcuate fashion between an inner radius and an outer radius of the discs.
When a disc drive is deenergized, the transducers are automatically moved to a storage location or xe2x80x9cparkxe2x80x9d location on the disc surfaces. The park location is typically adjacent and outside the inner or outer periphery of the data storage region of the disc and is typically called a landing zone. This landing zone typically does not contain any useable data as the transducer physically contacts the disc at rest. Consequently, any data stored in this area would likely be lost or compromised. In addition, the landing zone is typically roughened to minimize the stiction of the transducer against the disc surface.
Other disc drives utilize load ramps to facilitate removal of the transducers from the media to a parked position adjacent the discs. The load ramps in a disc drive are typically stationary, such that in the process of the transducer/suspension assemblies being unloaded from the media, the transducers are moved to the outer rim portion of the discs onto ramps which extend over the outer rim portions. They then traverse up the ramps to a park location off of the disc surfaces. In the reverse process, the transducers are loaded onto the media by the transducers moving down the stationary ramps onto the media. This convention requires that some of the disc surface toward the outside radius of the disc not be utilized for data, but for a tolerance band, which is required to ensure that the transducers load and unload onto and off the media at a desirable location without damaging data. This outside tolerance band dimension may be at least partially determined by a requirement that the transducer not contact the edge, or chamfer, on the outside radius of the disc. The inside tolerance band dimension location may be determined by a requirement of not landing on data. The tolerances are primarily due to the dimensionally inaccuracies of the load ramp and its location in relation to the media and transducer/suspension. These tolerances are sensitive to the angle of the load ramp. Another consideration is that, since the circumference of the disc is greatest at the outside radius, the outside area has the highest overall data capacity within a set radial distance. Therefore, restricting a tolerance band to be used for transducer load and unload, rather than using this region for data, is undesirable. Accordingly, there is a continual need for improvements in the art whereby disc drive performance can be optimized by utilizing more of the outer portions of the disc for data storage.
The present invention provides a solution to the undesirability of having a tolerance band on the outer margin of the disc for loading and unloading the transducer/suspension system. The present invention optimizes the number of data tracks available near the outer margins of the disc and also permit the heads carrying the transducers to land on the disc over data containing tracks. The present invention is a movable load/unload parking apparatus which preferably has an elongated pivoting parking member mounted adjacent the disc or discs for rotation about an axis parallel to the axis of rotation of the discs. The pivoting parking member has a pickup portion projecting from a central pivot portion and a crash stop portion projecting from the central pivot portion in a direction generally opposite to that of the load ramp portion.
The movable load ramp and crash stop member is operable between a first position and a second position. In the first position, the pickup portion has a distal end extending over a peripheral portion of the disc or discs to receive the distal end of the actuator arm and lift the transducer from its flying height above the disc surface as the actuator arm is rotated toward the outer diameter of the disc upon drive shutdown and hold the transducer in a parked position beyond the outer diameter of the disc during drive shutdown conditions. At the same time, the crash stop portion rotates away from the disc to permit the actuator assembly to rotate the actuator arm carrying the transducer beyond the outer diameter of the disc. During drive operation, the movable load ramp and crash stop member is located in a second position with the pickup portion away from the peripheral portion of the disc and the crash stop portion in a position to interfere with rotation of the actuator assembly beyond the outer diameter of the disc thereby preventing the transducer from going beyond the data region of the disc while allowing the transducer to read and write data to the disc in the peripheral region of the disc near the outer diameter of the disc. The elongated parking member is preferably biased toward the first position so that upon a power loss, the parking member automatically rotates to the first position.
These and other features as well as advantages that characterize the present invention will be apparent from a reading of the following detailed description and a review of the associated drawings.